Polymer-containing motor fuel composition



United States Patent The present invention relates to improved motor fuels for use in internal combustion engines and more particularly relates to gasolines having incorporated therein a certain combination of high and low molecular Weight polymeric additive agents which markedly reduce the formation of deposits, sludge and varnish in gasoline engines.

Despite the relatively high efficiency of modern gasoline engines, complete combustion of the fuel introduced into the combustion chambers of such engines seldom, if ever, occurs. Studies have shown that certain polynuclear aromatic compounds and other relatively high boiling materials present in gasolines are only partially burned and that the exhaust gases formed in the combustion chambers of gasoline engines contain trace amounts of hydrocarbons. Apparently these hydrocarbons undergo complex cracking, polymerization and oxidation reactions to form carbonaceous deposits which adhere to the upper part of the cylinder head, the valves, the piston tops and other surfaces in the engine with which the hot gases come into contact. When the lubricating oil subsequently comes into contact with hot metal surfaces, these materials react to form insoluble products. it has been shown that practically all the sludge in crankcase oils and most of the varnish on piston skirts, connecting rods, crankshafts and similar engine parts are thus due to constituents which were originally present in the gasoline.

Deposits, sludge and varnish formed in this manner seriously affect the operation of a gasoline engine. The role which combustion chamber deposits play in promoting surface ignition, spark plug fouling, rumble, octane requirement increase and similar combustion difficulties is generally well known. Less familiar but equally serious is the tendency of these foreign materials to cause malfunctioning of the engine lubricating system, to accelerate the rate at which the wear of engine parts occurs, to increase engine oil consumption, and to produce improper valve and piston ring operation, leading to serious losses in engine power. Because of these adverse effects, efforts have been made to improve the combustion in gasoline engines and decrease the formation of deposits, sludge and varnish by a variety of methods, including the use of solvent oils and other additives in the gasoline.

in the past, various detergent and dispersant type additives have been employed in the non-volatile, high boiling, crankcase mineral lubricating oil to aid in suspending these insoluble products, and to effect cleanliness of those engine areas where the lubricating oil came into direct liquid contact. The employment of high molecular weight polymeric additives in volatile fuels like gasoline has been generally avoided in the belief that the nonvolatile, high molecular weight and polymeric nature of these additives could only have a detrimental effect on upper engine cleanliness, such as in increasing the level of the intake valve underside deposits. Additionally, the effective functioning of these additives after high temperature combustion, together with the volatile fuel in a combustion chamber, was in considerable doubt.

In has now been discovered that a particular combination of a high molecular weight, ashless, oil soluble, V1. multifunctional type polymeric additive and a low molecice ular wei ht, ashless, oil soluble detergent additive effectively complement one another to provide a significant reduction in overall engine cleanliness when incorporated in a volatile motor fuel at very low concentration levels. This combination reduces and inhibits the formation or deposition of varnish, sludge, and gum in an internal combustion engine. Further, this unique and particular combination of additives formerly separately employed in heavy lubricating oils, functions to maintain a high clear1- liness level in the fuel lines and carburetor area. Moreover, this combination allows a reduction in deposit formation even in those areas not directly contacted with liquid gasoline fuel, such as the timing gear cover, the rocker arm cover, rocker arm assembly area, push rod chamber, crankcase, and crankshaft. The functioning of the polymeric combination is surprising in that it survives the combustion of the volatile fuel. A further unexpected advantage obtained by the use of the combined additives of the instantly described class is the marked reduction in engine deposit which is considerably superior to the use of each polymer when separately employed in gasoline. Thus, the applicants have discovered a unique method of directly promoting overall engine cleanliness by incorporating very small amounts of the additive combination in a volatile fuel, thereby giving marked advantages over the required incorporation of higher concentration levels in heavy mineral oils, and yielding far more beneficial results.

To obtain the beneficial results of the instant invention, the additive combination is incorporated in minor amounts sufficient to enhance overall engine cleanliness. The quantities employed will, of course, depend in part on the fuel components, the engine, and the driving conditions encountered, but normally are employed in very small quantities in a volatile fuel at a total active concentration level of between 0.001 .and 1.0 wt. percent and preferably between 0.005 and 0.20 wt. percent. The ratio of the V1. improver to detergent additive may vary between 5/1 and l/5 with a ratio of between 3/1 and 1/1 preferred. The additives may be directly incorporated in the motor fuel singly or in combination or in an oil concentrate form alone or together with other conventional fuel additives as described. Further, the polymeric additive agents may be incorporated in solvent oils such as light mineral hydrocarbon gasoline solvent oils such as naphthene or paraffin base, acid treated and neutralized distillate.

The relatively high molecular weight, ashless, oil soluble, V.l. improver multifunctional polymers may be those polymers such as described in US. application 769,991, U.S. Patent No. 3,015,546, filed October 28, 1953, and those polymers described in US. application 807, 987, US. Patent No. 3,058,818, filed April 22, 1959. These polymers include the terpolymers prepared by copolymerization of N-vinyl pyrrolidones, vinyl esters of short chain fatty acids like vinyl acetate and alkyl fumar ate, and those copolymers obtained by copolymerizing N-vinyl pyrrolidones and C to C alkyl acrylates and methacrylates.

The preferred high molecular weight, oil soluble, ashless, V.I. improver multifunctional polymers are obtained by copolymerizing maleic anhydride with an aliphatic ester of an a e-unsaturated dicarboxylic acid and a copolymerizable C to C alkylene ester of a C to C monocarboxylic acid. The preferred embodiment of this polymer includes the terpolymer obtained by copolymerizing maleic anhydride, vinyl acetate, and C to C alkyl fumarate. The preferred polymeric addititve agents are those terpolymers obtained by copolymerizing maleic anhydride, a vinyl ester of a short chain fatty acid, and a long straight chain C to C fatty alcohol ester of a butenedioic acid.

It is preferred that the esters of diand monocarboxylic acids used to form the copolymers of the present invention are so chosen that a mixture of relatively long and short aliphatic side chains is disposed along the polymer chain. The relatively long side chains may be provided by C to C aliphatic saturated or unsaturated, substituted or unsubstituted ester of a C to C u,,8-unsaturated dicarboxylic acids, e.g. esters derived from C to C fatty alcohols, preferably alkyl alcohols. Straight chain alcohols, branched chain alcohols, or a mixture of the two can be used. The preferred acids are a d-unsaturated conjugated dicarboxylic acids, such as a butenedioic acid like fumaric acid although malaic or itaconic acids may be used. Suitable esters include monoand di-C Oxo fumarate, tallow fumarate, lauryl rnaleate, stearyl fumarate, C Oxo furnarate, and cetyl itacouate, and the like. The relatively short side chains are preferably provided by using C to C alkylene esters of C to C carboxylic acids, preferably vinyl or allyl esters such as allyl and vinyl esters of short chain C to C fatty acids like vinyl acetate and allyl acetate. Minor amounts, e.g. 1 to molar proportions of other ethylenically unsaturated polymerizable organic monomers, especially those containing vinyl, vinylene, or vinylidene groups can also be used in preparing the copolymers of the invention, such as vinyl pyrrolidone, acrylates, styrene, vinyl ethers, butadiene, etc.

The molar proportions of the monomers preferably used in preparing the copolymers according to the present invention are:

The molar proportions of column A are especially preferred and those of column D are most preferred.

The weight average molecular weights of the VI. multifunctional additives may vary between 100,000 and 2,000,000 or more, e.g. 3,000,000, as determined by standard light scattering method, but preferably range between 500,000 and 2,000,000. Since the average molecular Weight may vary depending on the length and character of the side chains, that is, the butenedioic acid esters employed, a more effective method of designating the polymer is by the degree of polymerization which clearly defines the main polymer chain length.

The degree of polymerization is defined as the number of carbon atoms in the main polymer chain divided by two. The multifunctional V.I. polymers of this invention have a degree of polymerization between about 500 and about 8,000 or more, such as 10,000, but preferably between 1500 and 5,000.

The copolymers of the present invention may be prepared by any well known process, such as low temperature Friedel-Crafts polymerization, ionic or radiation polymerization processes. Free radical producing catalysts, e.g. peroxide type catalysts are particularly useful, such as benzoyl, acetyl, steroyl or urea peroxide or azo catalysts such as a,a-azo-bis-isobutyronitrile may be employed.

If a free radical catalyst which decomposes at a temperature above 70 C. is used to copolymerize the monomers, an improved copolymeric product is obtained compared with a similar product obtained using a free radical catalyst decomposing below 70 C., such as benzoyl peroxide. The preferred peroxide catalyst used in this improved process is organic alkyl and aryl peroxides such as alkyl perbenzoates and tertiary butyl perbenzoate. Other catalysts which may be used are tertbutyl hydroperoxide, 2,2-bis(tert-butyl-peroxy butane), di-tertiarybutyl peroxide, di-cumyl peroxide.

Another way of defining this improved process is that the copolymeric reaction is carried out at a temperature between and 200 C., using a peroxide catalyst which does not decompose below 70 C.

The catalyst may be used in the form of an oil solution or slurry, and the reaction is preferably carried out under an inert gas, e.g. nitrogen, the reactants being agitated, either by stirring or bubbling the inert gas through the mixture. The reaction is carried out for a period of time sufficient to copolymerize the reactants, but not for a time long enough to form an insoluble gel. A preferred criterion is to continue the reaction until the mixture reaches a viscosity of about 400 stokes at the reaction temperature and then dilute the reaction mixture with an oil, preferably a solvent oil of the type described, the copolymer being stripped under vacuum. The solvent oil or heavy mineral oil concentrate of the stripped polymer may then be incorporated in hydrocarbon motor fuels. The catalyst may then be used in minor amounts such as from 0.001 to 5.0 wt. percent, e.g. 0.1 to 2 wt. percent. These high molecular weight polymers are further described in British Patent 807,737, which is hereby incorporated by reference.

The low molecular Weight detergent inhibitor additives of the invention may comprise those oil soluble, low molecular weight, e.g. 150 to 900, metallic salts such as the alkali and alkaline earth salts of petroleum sulfonates, alkyl phenol sulfides, phenates, and the like such as calcium sulfonate, barium phenate, calcium dodecyl phenol sulfide and the like. These additives are not as effective as the preferred additives due in part to their metallic ash-forming character.

The preferred low molecular detergent additives of the invention are those oil soluble, ashless, phosphosulfurized, hydrolyzed, neutralized polymers prepared by the reaction of a hydrocarbon with a sulfide of phosphorous.

The phosphosulfurization agent may be P 8 P 8 P 3 P 5 or their mixtures, or mixtures of elemental phosphorus and sulfur or other materials. A sulfide of phosphorus, especially phosphorus pentasulfide (P 5 is preferred. Generally, in the range of about 1.0 to 50.0% by wei ht, based on the hydrocarbon, of phosphosulfurizing agent is used. A preferred range is about 5 to 25, e.g. 10 to 20, wt. percent.

Hydrocarbons to be treated should, of course, be reactive With the phosphosulfurizing agent. They include paraflins, olefins, diolefins, acetylenes, aromatics, cyclic aliphatics, and various mixtures of these such as are found in petroleum fractions, condensation products of mtroleum fractions, hydrogenated coals, synthetically produced hydrocarbons and the like. Preferred are lubricating oil distillates and base stocks such as bright stock residuums and the like and polyolefins.

The phosphosulfurized hydrocarbons which are utilized as one constituent of the additive combination of the invention are prepared by reacting a C to C olefin polymer with a sulfide of phosphorus. Olefinic polymers prepared by the polymerization or copolymerization of low molecular weight olefins and diolefins such as ethylene, propylene, butylene, isobutylene, butadiene, isoprene, and cyclopentadiene, are suitable materials for the phosphosulfurization. Polymers of mono-olefins wherein the molecular weight ranges from about 500 to about 20,000 and preferably ranges from about 600 to about 10,000, e.g. 700 to 2000 are particularly effective in preparing the phosphosulfurized hydrocarbons of the invention. The most preferred polyolefin employed is a polyisobutylene or polybutene having an average molecular weight of 700 to 1200, e.g. 940. The average molecular weight of the P 5 treated polyolefin is of some importance in that it has been found that there is a decrease in effectiveness With decreasing molecular weight. For example, 15 P S polybutene of 940 M.W. is quite effective in reducing the sludge demerit rating in gasoline, while 30 5 P S 100 polyisobutylene of 660 M.W. is of reduced effectiveness and 15 P S 100 polyisobutylene of 330 M.W. is relatively ineffective. Another preferred hydrocarbon is a bright stock lubricating oil residuum.

One method of carrying out such a polymerization reaction is to employ a Friedel-Crafts catalyst such as boron fluoride or aluminum trichloride at low temperatures in the range of from about F. to about 40 F. Other methods familiar to those skilled in the art, carried out at higher temperatures and with other polymerization catalysts may also be used as described, for example, in

US. Patent 2,768,999.

The resulting acidic phosphosulfurized hydrocarbon reaction product is then hydrolyzed by steam stripping the product at a temperature of between 100 C. and 200 C., e.g. 140 to 160 C., for a period of time, e.g. 1 to 6 hours, sufiicient to reduce the volatile by-product odor and to bring the acid number to at least 25 and the sulfur content to less than 1.5 wt. percent. This method is more fully described in British Patent 838,928 and British Patent 792,553, hereby incorporated by reference.

The hydrolyzed phosphosulfurized polyolefin or bright stock is further stabilized and improved by reacting the acidic hydrolyzed product with a neutralizing agent such that its titratable acidity is at least partially reduced. Neutralizing agents include the alkali and alkaline earth and metal hydroxides, carbonates, and oxides, but preferably include those ashless basic reagents such as ammonia and alkyl and aryl substituted amines. The amount of neutralizing agent employed is usually between 1 to 50% by weight of the acidic product, e.g. 1 to 20 wt. percent, or from 1 to about 10 moles, e.g. 2 to 5 moles, of agent to moles of acidic product, e.g. 2 to 6 moles.

A most preferred class of basic reagents includes organic epoxide compounds such as aryl substituted alkyl epoxides like styrene epoxide; alicyclic epoxides like cyclopentene epoxide; halosubstituted alkylene epoxides such as chloropropylene oxide; and particularly C to C alkylene oxides such as ethylene oxide, propylene oxide, butene oxide, and the like. From 1 to moles of these epoxides are reacted with each mole of acidic product as described more fully in British Patent 792,593, hereby incorporated by reference. Although the neutralized product is preferred and the hydrolyzed and neutralized product most preferred, the untreated P 8 polyolefin reaction product itself may be employed but generally would somewhat reduce the effectiveness.

A further preferred basic reagent to neutralize the acidic product includes the use of from 1 to 10, e.g. 1 to 3, moles per mole of acidic product or sufficient basic reagent to stoichiometrically neutralize the acidic product of an amide of a carbonic acid or nitrogen or sulfur analogue thereof. Suitable compounds include those having the general formula:

wherein X is oxygen, an irnino nitrogen, or a C to C alkyl mono-substituted imino nitrogen, or sulfur, but preferably oxygen; R is a radical selected from the group consisting of hydrogen, alkyl, cycloalkyl, alkenyl, arene, and aryl radicals or combinations thereof with hydrogen and C to C alkyl radicals preferred; and R'" is a radical selected from the group consisting of ester groups such as OR where R is an alkyl, cycloalkyl, alkenyl arene, and aryl radical, preferably a C to C alkyl radical; and N(R) and ON(R) wherein R is as defined for R. These basic reagents particularly include, but arenot limited to, urea, thiourea, guanidine, the ammonium and amine salts of carbonic acid, e.g. ammonium carbonate, C to C fatty primary amine salts of carbonic acid, urethanes such as ethyl carbamate, butyl carbamate, uryl- 6 enes, tetraalkyl guanidines like tetramethyl guanidine, quaternary ammonium carbamates such as dimethyl dioleyl carbamates and the like.

The motor fuels in which the polymeric additives are employed in order to reduce the formation of deposits sludge and varnish are conventional petroleum distillate fuels boiling in the gasoline boiling point range employed in internal combustion, preferably spark ignition, engines. They are supplied in a number or" different grades depending upon the type of service for which they are intended. The copolymers may be employed in all of these grades but are particularly useful in motor and aviation gasolines. Motor gasolines as referred to in connection with the present invention are defined by ASTM Specification D-439-58T in Types A, B and C. They are composed of a mixture of various types of hydrocarbons including aromatics, olefins, paraffins, isoparaffins, naphthenes and, occasionally, diolefins. Those motor fuels containing at least 10% by weight of thermally or catalytically high aromatic components may be especially benefited from the instant invention. Suitable gasolines to which the polymeric additives of the instant invention may be added are those gasolines having an octane number range of 83 to 105 or higher, such as a clear octane number of over 90, for example, over or 100, and comprising over 20% by volume of aromatic hydrocarbons and less than 30% by volume of olefinic hydrocarbons. They are derived from petroleum crude oil by refining processes such as fractional distillation, catalytic cracking, hydroforming, alkylation, isomerization, polymerization and solvent extraction. Motor gasolines normally have boiling ranges between about 70 F. and about 450 F., while aviation gasolines have narrower boiling ranges of bet\ 'een and 330 F. The vapor pressures of gasoline as determined by AST M Method D86 vary between about 7 and about 15 p.s.i. at 100 F. The copolymers may also be employed in aviation gasolines which have properties similar to those of motor asolines, but normally have somewhat higher octane numbers and narrower boiling ranges. The properties of aviation gasolines are set forth in US. Military Specification MIL-F- 5572 and ASTM Specification D-91057T.

The copolymeric additives employed in accordance with the invention may be used in gasolines with other additive agents conventionally used in such fuels. It is common practice to employ from about 0.5 to about 7.0 cc./gal. of alkyl lead antiknock agents, such as tetraethyl lead, tetramethyl lead, dimethyl diethyl lead or a similar lead antiknock agent or olefinic lead antiknock agents such as tetravinyl lead, triethyl vinyl lead, and the like, or a combination thereof, in both motor gasolines and in aviation gasolines, e.g. 1.0 to 3.0 cc. of tetraethyl lead-tetramethyl lead combination. Antiknock agents may also include other organometallic additives containing lead, iron, nickel, lithium, manganese and the like. Other additives such as those conventionally employed in gasolines may be used such as corrosion inhibitors, antioxidants, antistatic agents, lead octane appreciators like t-butyl acetate, auxiliary scavengers like tri-fi-chlorethyl phosphate, dyes, anti-icing agents like isopropanol, hexylene glycol, and the like.

Catalytically and thermally cracked and reformed gasolines containing a high aromatic content whether leaded or unleaded, are particularly prone to yield excessive manifold deposits and are improved by addition of the applicants polymeric additives.

Lead antiknock agents are usually employed in conjunction with halogenated hydrocarbon scavenger agents boiling in the range between 50 and 250 R, such as ethylene bromide, ethylene chloride, and the like, in concentrations of from 0.5 to 3.0 theories, with preferred concentration levels of from 0.8 to 1.5 theories of ethylene bromide used alone or 0.8 to 1.5 of ethylene dichloride and 0.3 to 0.8 of ethylene dibromide when a mixed scavenger is used.

The preparation of the low molecular weight dispersant polymers may be illustrated by the following examples.

EXAMPLE 1 The following monomer mixture is prepared:

Percent by wt. Lauryl fumarate 75.2 Lauryl alcohol (reaction modifier) 2 Vinyl acetate 18.8 Maleic anhydride 4 The monomer mixture is then divided into two parts, part A being copolyinerized at 60 C. using 1 wt. percent benzoyl peroxide and part B being copolymerized at 90 C. using 0.4 wt. percent tertiary butyl perbenzoate. Copolymerization is continued in both instances until a reaction mixture having a viscosity of 400 stokes at the reacton temperature, and the copolymeric products diluted with an SAE type mineral oil or a solvent oil. The solution is then stripped under a reduced pressure of 5 mm. Hg at 100 C. until the solution contained of the active polymer. The benzoyl peroxide polymer is designated as polymer A With the t-butyl perbenzoate designated as polymer B, each polymer having a chain length of about 3,000 to 10,000 carbon atoms.

EXAMPLE 2 The procedure of Example 1 is repeated exactly except that the materials polymerized are as follows:

Mole percent Di-Cg Oxo fumarate 17.8 Di-tallow fumarate 7.4 Vinyl acetate 71.8 Maleic anhydride 3.0

The di-taliow fumarate is prepared by esterifying fumaric acid with alcohols derived from the hydrogenation of tallow. These tallow acids contain a straight chain alcohol mixture comprising about 1 wt. percent C alcohol, 6 wt. percent C alcohol, 30 Wt. percent C alcohol, wt. percent C alcohol, and 3 wt. percent C alcohol and had an average molecular Weight of about 265. The di-C 0x0 fumarate is obtained by esterifying fumaric acid with C 0x0 alcohols. The Oxo process for preparing alcohols is described in US. Patents 2,327,066, 2,504,682, etc. In brief, the C Oxo alcohols are prepared by reacting an olefin prepared by the reaction of butylene and propylene with carbon monoxide and oxygen to form a mixture of aldehydes winch were hydrogenated. The di-C Oxo fumarate and di-tallow fumarates are mixed. The resulting mixture has an average molecular weight of about 420. Two Wt. percent of benzoyl peroxide based on the total weight of the polymerizable materials is used as a catalyst. Two wt. percent of lauryl alcohol based on the total weight of the polymerizable materials is used as a moderator. The polymer was designated as polymer C and has a chain length of 3,000 to 10,000 carbon atoms.

EXAMPLE 3 The procedure of Example 2 is repeated exactly except that the materials polymerized are as follows:

Mole percent Di-C 0x0 fumarate 14.6 Di-C 0x0 fumarate a- 6.6 Di-tallow furnarate 4.0 Vinyl acetate 71.9 Maleic anhydride 2.9

The di-C Oxo fumarate is prepared by esterifying fumaric acid with a C Oxo alcohol. The C Oxo alcohols are prepared by the 0x0 process by reacting propylene tetramer with carbon monoxide and hydrogen to form a branched C aldehyde which is hydrogenated to form the C alcohol. The three fumarates are mixed to obtain a fumarate mixture having an average molecular weight of about 420. This polymer is designated polymer D.

EXAMPLE 4 A low molecular weight, oil soluble, ashless, phosphosulfurized detergent designated polymer E is obtained by treating a polyisobutylene of about 900 average molecular Weight with about 15% by weight of P 8 for 8 hours at a temperature of from 180 to 220 C. The resulting acidic product was then blown with steam for about 4 hours at a temperature of to 120 C. to remove the volatile byproduct odor and effect hydrogenation. The steam-blown product with about 50 Wt. percent diluent oil is then reacted with about 8 wt. percent of ethylene oxide in the presence of BB; ether or sodium hydroxide for about 4 hours at 285 F. The resulting polymer contained about 1.8 wt. percent phosphorus and about 0.9 wt. percent sulfur.

EXAMPLE 5 The above procedure of Example 4 is substantially repeated except that the acidic steam-blown product is treated with about 4.5 wt. percent urea to yield a polymer product designated polymer F and comprising about 1.8 wt. percent phosphorus and 1.1 wt. percent sulfur and characterized by having an acid number of about 20.

EXAMPLE 6 The above procedure of Example 4 is substantially repeated except that the acidic product is not blown with steam and is reacted with 5% by weight of propylene oxide to yield an oil soluble product designated polymer G.

EXAMPLE 7 A bright stock solvent having a viscosity of about 32 centistokes at 210 F. is treated with about 10% by weight of P 5 at 430 F. for 8 hours. The resulting acidic product is then treated with about 10% by weight of ethylene oxide at 285 F. for 8 hours to give an oil soluble product designated polymer H comprising about 2.1 wt. percent phosphorus and about 3.6 wt. percent sulfur.

EMMPLE 8 An ashless, oil soluble, detergent designated polymer I is prepared by treating a polybutene of about 1200 to 1400 molecular weight with about 10% by weight of P 8 as in Example 4, to produce acidic polybutene phosphosulfurized detergent product.

EXAMPLE 9 The acidic product of Example 8 is hydrolyzed by blowing with steam for at least 6 hours at a temperature of about 100 to C. to produce an oil soluble product having an acid number of at least 50 and with a reduced by-product odor designated polymer K.

EXAMPLE 10 The steam-blown product of Example 9 is substantially neutralized by the addition of a stoichiometric quantity of guanidine to produce a neutralized polymer designated polymer L.

EXAMPLE 11 Example 10 is repeated employing a quaternary ammonium carbamate of trisoya methyl carbamate to yield a product called polymer M.

EXAMPLE 12 To demonstrate the effectiveness of the additive polymeric combination, an engine test employing a motor gasoline having no polymeric additives and having incorporated therein the polymeric additives singly and then in combination was carried out. The gasoline employed had the following characteristics.

Base gasoline inspections ASTM distillation, Method D-86:

Initial boiling point, F 91 10% boiling point, F. 127 50% boiling point, F. 237 90% boiling point, F. 355 Final boiling point, F. 428 Reid vapor pressure, p.s.i 11.9 ASTM gum, rug/100 ml. 2.6 ASTM breakdown time, min 960+ FIA analysis:

Vol. percent saturates 51.0 Vol. percent olefins 15.7 Vol. percent aromatics 33.3 Tetraethyl lead, cc./gal. 2.18 Research octane No. 97 Motor octane No. 87

Samples of the base gasoline and samples of the same gasoline containing very small amounts of the polymeric additives singly and in combination were employed in a sustained engine test designed to evaluate gasoline cleanliness performance. A 1950 6-cylinder Chevrolet engine attached to a dynamometer on a test stand was operated on repeated cycles for a period of about 110 hours and 220 hours.

At the conclusion of the 110 hours and 220 hour periods, the engine was inspected and various parts were rated in demerit steps for sludge, deposits and varnish on a demerit scale ranging from O to 10, indicating the presence of no deposits at all and 10 signifying that the particular part rated had the maximum amount of deposits it was capable of holding. The results of these ratings are set forth in the following Table I.

10 EXAMPLE 13 A superior aviation gasoline providing enhanced engine cleanliness characteristics is prepared by incorporation of about 0.008 wt. percent of polymer F and about 0.015 wt. percent of polymer A in said gasoline having an initial ASTM boiling point of about 105 F. and an ASTM boiling point of about 315 F. and containing about 4 cc./ gallon of tetraethyl lead and 1.0 theory of ethylene dibromide.

EXAMPLE 14 EXAMPLE 15 A regular gasoline motor fuel having an ASTM distillation point of less than 210 F. is greatly improved in engine cleanliness charatceristics after an operating period of more than 110 hours by the addition of about 0.007 wt. percent of polymer H and 0.01 Wt. percent of polymer C.

EXAMPLE 16 A spark ignition internal combustion engine operating on the Otto cycle and having a compression ratio of between 7/1 and 10/1 has a reduced tendency to form TABLE I.ENGINE CLEANLINESS RESULTS Visual demerit ratings Engine N o 1 2 3 4 No +0.010% polymer D +0.015% polymer D +0.015% additive +0.005% polymer E polymer E Test Time (hrs) 110 110 220 100 220 110 Engine part (sludge rating)- Cylinder head top. 0. 25 0 0 0 0. 25 0. 25 Rocker arm assemb 0. 50 0 0 0 0.25 0.25 Rocker arm cover 0. 75 0 0.25 0 0.25 0.25 Crankshaft 0. 50 0 0 0 0. 50 0 Timing gear cover- 0. 75 0 0. 50 0. 25 Push rod chamber 0. 25 0 0 0 0. 25 0 Push rod chamber cover 0. 75 0 0. 25 0.25 0.50 0.25 Crankcase bottom 0. 75 0. 25 O. 25 O. 25 0.50 O. 25 Oil screen O 0 0 0 0 0 Averge sludge rating O. 50 0. 03 0. 08 0. 07 0.33 0. 17 Piston skirt varnish 7. 5. 96 8. 25 6. 21

The foregoing results demonstrate that the VI. multifunctional polymer and the low molecular weight phosphosulrurized detergent polymer in combination gave significantly efiective overall engine cleanliness. This combination at extremely low concentration levels further apparently coacted to produce especially superior engine cleanliness much greater than would be expected from their individual performances.

The data demonstrate that singly the v.1. multifunctional high molecular weight polymer was effective in preventing excessive deposits in a test period of 110 hours, but rapidly became degraded by further engine operation so that at the end of the 220 hour period the deposit level had increased alarmingly. The detergent additive, although enhancing engine cleanliness over the use of the base fuel alone, failed to give adequate protection at the end of the 110 hour test period. The combinations of ese additives at lower concentration levels as low as 0.005 wt. percent for the detergent complemented each other to provide excellent and markedly improved engine cleanliness both at the end of the 110 and 220 hour test periods.

sludge and varnish on upper engine areas not having direct liquid contact with the crankcase lubricating oil by using a gasoline fuel having incorporated therein about 0.006 wt. percent of polymer F and about 0.015 wt. percent of polymer D.

EXAMPLE 17 The internal surface cleanliness of the intake manifold, carburator, fuel lines, and fuel filter of an engine is upgraded by the presence in a volatile gasoline having a free sulfur content of less than 0.15 wt. percent and an ASTM gum level greater than 2.0 mg./ 100 ml. of about 0.02 wt. percent of polymer C and about 0.01 wt. percent of polymer E and between 0.1 and 0.8 vol. percent or" a hydrocarbon naphthene base acid treated distillate solvent oil having an SUS viscosity of between 50 and at F.

EXAMPLE 18 Regular commercial gasolines as described containing cracked components and which tend to produce deposits during the operation of internal combustion engines may 1 i be upgraded in cleanliness characteristics by incorporation of the following combinations of additives of about 0.010 wt. percent of dispersant and 0.005 wt. percent of the detergent, e.g. polymers A and F, A and G, B and I, B and L, B and H, A and H, C and M, C and E, C and K, and the like.

In addition, these polymers may be injected in concentrate form singly or in combination into the intake manifold, carburetor, fuel lines, or engine combustion chamber in order to promote overall engine cleanliness. Periodic addition of these polymeric additives will enhance engine cleanliness.

What is claimed is:

1. An improved motor fuel composition comprising a major amount of a liquid petroleum motor fuel boiling in the gasoline boiling range and about 0.001 to about 1.0 wt. percent of an additive comb nation of (l) a high molecular weight polymeric additive obtained by copolymerizing 1 to 6 molar percent of maleic anhydride with from 20 to 50 molar percent of an ester of a C to C unsaturated dicarboxylic acid and a C to C fatty alcohol and from 40 to 80 molar percent vinyl acetate to yield a polymer having an average degree of polymerization between 500 and 10,000 and (2) a low molecular Weight detergent polymer obtained by phosphosulfurizing polyisobutylene and having a molecular weight of between 600 and 10,000, said high and low molecular weight polymers being present in a weight ratio of between 5/1 and 1/5.

2. A fuel composition as defined in claim 1 wherein said detergent polymer is blown with steam at temperatures between 100 and 200 C. until the acid number of the product is at least 25. V

3. A fuel composition as defined in claim 1 wherein said detergent polymer is neutralized with from 1 to moles of a C to C alkylene oxide.

4. A fuel composition as defined in claim 1 wherein said detergent polymer is neutralized with from 1 to 10 moles of an amide having the general formula:

R X R N-i lN R R wherein X is selected from the group consisting of oxygen, sulfur, an imino nitrogen, and a C to C alkyl monosubstituted imino nitrogen, and R is a radical selected from the group consisting of hydrogen and C to C alkyl groups.

5. A fuel composition as defined in claim 1 wherein said ester is a dialkyl fumarate.

6. A fuel composition as defined in claim 1 wherein said weight ratio varies between 3/1 and 1/ 3.

7. A motor fuel boiling in the gasoline boiling range to which has been added between 0.001 and 1.0 wt. percent of a polymeric additive combination of a high and low molecular weight polymer, the high molecular weight additive having a molecular weight of from 100,000 to 3,000,000 and being obtained by copolymerizing from 1 to 6 molar percent maleic anhydride with from 20 to 50 molar percent of an ester of a butenedioic acid and a C to C fatty alcohol and from 40 to molar percent Vinyl acetate and the low molecular weight additive is obtained by phosphosulfurizing a polyisobutylene having a molecular weight between 600 and 10,000, and treating the acidic product with from l to 10 moles of a neutralizing agent per mole of acidic product, said agent being selected from the group consisting of C to C alkylene oxide and urea, said high and low polymer being present in a weight ratio between 5/1 and 1/ 5.

8. A fuel as defined in claim 7 wherein said butenedioic ester is dialkyl fumarate. i

9. A fuel as defined in claim 7 wherein said alkylene oxide is ethylene oxide.

10. A fuel as defined in claim 7 wherein said acidic phosphosulfurized polyisobutylene is blown with steam at a temperature of between and 200 C. for a sufficient time to bring the acid number to at least 25.

11. A motor fuel boiling in the gasoline boiling range to which has been added between 0.001 and 1.0 wt. percent of a polymeric additive combination of a high and low molecular weight polymer, the high molecular weight additive having a molecular weight of from 100,000 to 3,000,000 being obtained by copolymerizing from 1 to 6 molar percent maleic anhydride with from 20 to 50 molar percent of a fatty acid ester of dialkyl fumarate and from 40 to 80 molar percent of vinyl acetate, and the low molecular weight additive is obtained by phosphosulfurizing isobutylene of between 700 and 2000 molecular weight, said acidic phosphosulfurized polyolefin being blown with steam at a temperature of between 100 and 200 C. for a sufiicient time to bring the acid number to at least 25, and treating the acidic product with a neutralizing agent selected from the group consisting of ethylene oxide and urea with from 1 to 10 moles of agent to mole of acidic product, said high and low polymer being present in a weight ratio between 5/1 and l/5.

References Cited by the Examiner UNITED STATES PATENTS 2,768,999 10/1956 Hill 25232.7 X 2,781,319 2/1957 Barnum et al 44-62 X 3,015,546 1/1962 Michaels et a1. 4463 X 3,087,893 4/1963 Agius et al 4470 FOREIGN PATENTS 792,553 3/1958 Great Britain.

807,737 1/ 1959 Great Britain.

838,928 6/1960 Great Britain.

DANIEL E. WYMAN, Primary Examiner. 

1. AN IMPROVED MOTOR FUEL COMPOSITION COMPRISING A MAJOR AMOUNT OF A LIQUID PETROLEUM MOTOR FUEL BOILING IN THE GASOLINE BOILING RANGE AND ABOUT 0.001 TO ABOUT 1.0 WT. PERCENT OF AN ADDITIVE COMBINATION OF (1) A HIGH MOLECULAR WEIGHT POYMERIC ADDITIVE ABTAINED BY COPOLYMERIZING 1 TO 6 MOLAR PERCENT OF MALEIC ANHYDRIDE WITH FROM 20 TO 50 MOLAR PERCENT OF AN ESTER OF A C4 TO C6 UNSATURATED DICARBOXYLIC ACID AND A C8 TO C22 FATTY ALCOHOL AND FROM 40 TO 80 MOLAR PERCENT VINVY ACETATE TO YIELD A POLYMER HAVING AN AVERAGE DEGREE OF POLYMERIZATION BETWEEN 500 AND 10,000 AND (2) A LOW MOLECULAR WEIGHT DETERGENT POLYMER OBTAINED BY PHOSPHOSLFURIZING POLYISOBUTYLENE AND HAVING A MOLECULAR WEIGHT OF BETWEEN 600 AND 10,000 SAID HIGH AND LOW MOLECULAR WEIGHT POLYMERS BEING PRESENT IN A WEIGHT RATIO OF BETWEEN 5/1 AND 1/5. 